The present invention relates generally to aquarium filtering systems and, more particularly, to an external aquarium filter utilizing a pump impeller for drawing contaminated water into an intake assembly inserted into the aquarium tank, pumping it through the filtering compartment of the filter, and then back into the aquarium tank. Even more particularly, the present invention relates to windows formed in the part of the collar surrounding the impeller and provided for discharging water pumped by the impeller from the intake assembly into the intake chamber of the filter.
Aquarium filters are typically utilized for the aeration and filtration of the aquarium water and at the same time, to provide circulation to such water. One type of aquarium filter is an externally mounted filter which houses filtration equipment and includes a pumping mechanism which induces the circulation of water from the aquarium tank through the filtration equipment and then returns the clean water to the aquarium. Such filter is described in U.S. Pat. Nos. 4,512,885 and 4,602,996 assigned to the assignee of the present invention, both of which are incorporated herein by reference.
In order to provide circulation of the water, a suitably adapted pumping mechanism is provided, a portion of which is within the water flow path. A motor stator is hermetically enclosed in a compartment below the intake chamber, and a rotor is magnetically coupled to the stator and positioned directly within the flow path. An impeller is coupled to the rotor such that it rotates with the rotor upon energization of the motor stator.
An intake assembly is provided in order to supply the contaminated aquarium water to the filter. The intake assembly includes a U-shaped intake tube having its inlet situated in the aquarium tank and its outlet seated in the intake chamber of the filter. The impeller is received in a collar projecting upward from the motor unit and into which sits the outlet end of the intake tube. Openings, respectively facing the front and the rear wall of the intake chamber, are provided in the peripheral wall of the collar at the level of the impeller vanes to permit the contaminated water drawn into the intake assembly to be discharged out of the intake tube and into the intake chamber from where it can flow into the filtering compartment, where the water is filtered and from which the clean water is returned into the aquarium.
The openings in the intake chamber walls are typically of the same size and diametrically opposed to each other relative to the central axis of the collar. A problem with such otherwise satisfactory opening arrangement occurs when a smaller power filter housing is used. In this case the front opening defined at the impeller output is located rather close to the front wall of the intake chamber of the filter housing. This limited spacing can cause turbulence in the flow of water in the filter even causing a possible upward surge of the water which can also lead to turbulence at the top surface of the water in the filter which may spill over the back edge of the filter, or which may spill over the intake chamber overflow on the aquarium side of the filter, prematurely signalling a clogged filter cartridge condition to the user.